How to Combine MilliBox and SAF Compact Spectrum Analyzer

The MilliBox anechoic test chamber and it’s 3D gimbal solution is an excellent modular system for mmwave engineers. If you add the Compact Spectrum Analyzer from SAF Tehnika, you can build a cost-effective system integration for day-to-day antenna measurements at a fraction of the cost of any chamber with a Keysight or Rohde & Schwarz spectrum analyzer.

The SAF Spectrum Compact is priced similar to a harmonic mmWave mixer, but is a full self-contained compact integrated spectrum analyzer for power measurements, not requiring any additional instruments to work.

The SAF Spectrum Compact fits inside MilliBox

The pictures on the right shows the spectrum analyzer mounted directly on the MilliBox horn mount.

As the whole instrument will be inside the chamber, reflection shielding of the instrument can be done by using a small piece of absorber. There is no need for any kind of adhesive. To mount the absorbing material you simply cut a minor cross directly in the absorber. When you pull the absorber over the horn mount you will get a tight fit around the horn and the absorber will stay in place.

Custom SAF adaptor for the MilliBox horn mount

The SAF spectrum analyzer can easily be mounted on the MilliBox horn mount with our custom SAF adapter. No mechanical modifications required.

The horn mount is designed with a detachable top to change polarization, and the SAF adapter slides directly into the horn mount socket.

The SAF adapter is 3D-printed in ABS plastic, and has a firm grip of the spectrum analyzer.

We can make the model available as STL and STEP if you wish to modify it.

The external interface is serial-over-USB (the red cable). This allows you to remotely query the spectrum analyzer for power measurements.

You can use the SAF Spectrum Compact application manually for trials, but typically it would be automated through the MilliBox python code, which also controls the gimbal positioning.

The flow of the MilliBox control code with the SAF spectrum analyzer looks like this:

The control code moves the gimbal to position H, V

The spectrum analyzer is queried for power data

The gimbal is queried for position errors (MilliBox gimbals are all using closed-loop positioning)

Control code writes H, V, power, and any position errors to a CSV file